6/13/2010 11:00 AM PDT BY TMZ STAFF

Joe sat down with News of the World to explain his theory, that he was concerned that Michael was "looking kinda funny and and frail" and asked Katherine to see Michael to "keep him cheered up." But Joe says Katherine refused because she didn't want to invade his privacy.

Joe says he and Katherine argued about it before Michael's death, but Katherine was firm.

Joe says after Michael died, he said to Katherine, "I said this would have never happened if you had went and been with him."

Joe -- who was intentionally cut out of Michael's will -- is fighting to get an allowance from the estate. And get this -- we're told Katherine has been giving Joe money and going along with his efforts to earn a living off MJ.